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East Coast winter storm, February 13th-14th, imminent (Part II)


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W quasi high bridging in as main high retreats west i had more hope w this system than a day ago but the euro is really givin forecasters headaches in sne

 

 

The euro actually doesn't change snowfall amounts THAT much in SNE despite the bizarre evolution and warmer peak. It just brings taint further inland...but its more of an academic point than something that significantly alters snowfall. It flips back to snow for several hours to end it as a bit of a CCB tail comes through.

 

Its more of just how intense that front end stuff is...this run is weaker but it seems to last longer...versus shorter and more intense/heavy.

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SQL is a problem.

As is every storm one should use as many tools as possible. Don't take one run, one model as a carved-in-stone solution. The see-saw waffles are expected, the bias of each run leading up to onset are known but yet peoples reaction is as predicable as a sunset. Aside from writing styles a IMBY emotional investment always rings through. Coworkers before the storm kiddingly remark "you'll get it right the day after". In reality that is the only true forecast.

Keeping the course and taking every run in stride. No matter the outcome IT'S A BIGGY.      

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The euro actually doesn't change snowfall amounts THAT much in SNE despite the bizarre evolution and warmer peak. It just brings taint further inland...but its more of an academic point than something that significantly alters snowfall. It flips back to snow for several hours to end it as a bit of a CCB tail comes through.

Its more of just how intense that front end stuff is...this run is weaker but it seems to last longer...versus shorter and more intense/heavy.

In regards to taint - is it likely still frozen rather than plain rain?
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The Box accum maps probs show how longitude is > than latitide wrt snow in their minds.

Kev has better snow probs for 6,8, 12 inches then locals just west of 495 (like dracut) on those maps.

 

I'm not sure if those are updated probabilty maps or not, but they reflect their thinking of the jackpot being in the central CWA.  I guess they're thinking lower NW due to qpf and lower to the east due to more tainting.

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You can see how a decrease in omega effects temp profiles. Big lift fights off warmth, so you lose dynamics and you allow warmer air to penetrate inland. This is partly what the GFS was doing, especially the earlier runs. The front end job didn't change that much, it's just that the mix and dryaslot get further west.

 

I still have a hard time with a bowling ball near Hatteras, but it's not impossible. It will be interesting to see if ensembles agree.

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I think jackpots will be in NNE/berks/far nw ct/extreme northern middlesex county at this point unless something major changes. Mid levels tracks and banding favor to our north combined with the potentially modeled taint for many areas of SNE. This is subject to change right now still. Most still see several inches of snow before taint and many areas would verify warning totals even on the EURO. This is without considering the flip back to snow at the end of the funky EURO evolution. Bottom line my point is that even on the worst model runs for SNE many still do quite well leading to a positive gain in the snowpack and potentially a very enjoyable storm away from extreme S CT/SE MA/ extreme coast of E MA. Subject to CHANGE!

 

Watch the ensembles as they come out. That will definitely be very important.

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You can see how a decrease in omega effects temp profiles. Big lift fights off warmth, so you lose dynamics and you allow warmer air to penetrate inland. This is partly what the GFS was doing, especially the earlier runs. The front end job didn't change that much, it's just that the mix and dryaslot get further west.

I still have a hard time with a bowling ball near Hatteras, but it's not impossible. It will be interesting to see if ensembles agree.

Noob question - are the ensembles based on different calculations? Is that why they may be different?
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Noob question - are the ensembles based on different calculations? Is that why they may be different?

 

To put it simply, each member has different physics and parameterizations to better account for "chaos" in the atmosphere. The idea is to get a better idea and sample of possible outcomes and blend them in. The problem is that the resolution of these models is less than the op run which means that the solution sometimes is not totally correct either. More often than not, it's a much better way to look at solutions...especially beyond 60hrs out. We are near the point of handing off the baton from ensembles to OP runs though.

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Noob question - are the ensembles based on different calculations? Is that why they may be different?

The way we learned it in college ... each individual member runs "perturbed" versions of the physical equations.  They are not derived at random, however; each version is processing altered physical equations known to work in various circumstances. Example, there are different convective parameterizations they can employ...etc...etc.   

 

The idea is that if one or more processes are favored in a given pattern, the particular ensemble member that focuses on those may perform better than the others.  But also, the blend of all of them caries deterministic weighting because every process is involved at any given time, it's just a matter of how much, which is not really possible to define with current sampling/calculation technology.  So the mean of the ensembles sometimes outscores the primary (operational) version.  Just a way to atone for chaos, even though there really is no way to do so given the current state of the art.

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the server has been fine. It's some other issue...possibly software related. We have an outside guy that's going to look at it.

 

Just so you know and I'm sure you do...it's been happening for a few weeks. I get errors periodically that dump to the DB crash page even when we're tracking an OES event and there's nothing else going on.  Also, the home page has no link to the models or forums even when logged in.

 

Euro looks pretty good through 6 hours when compared to obs and the RUC analysis etc.  Good luck to forecasters with this one.

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You can see how a decrease in omega effects temp profiles. Big lift fights off warmth, so you lose dynamics and you allow warmer air to penetrate inland. This is partly what the GFS was doing, especially the earlier runs. The front end job didn't change that much, it's just that the mix and dryaslot get further west.

 

I still have a hard time with a bowling ball near Hatteras, but it's not impossible. It will be interesting to see if ensembles agree.

 

On Wunder the old 12z is still up...kind of amazed by the inconsistency run to run on the Euro even now at h48.  Really struggling with the kicker placement and attempted interaction.  Slight timing change and these NW tracks go poof.  Slightly more of a change in that direction and it's congrats Lake Placid.

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Pending complete 12z review.  HPC/WPC Model Discussion.

MODEL DIAGNOSTIC DISCUSSIONNWS WEATHER PREDICTION CENTER COLLEGE PARK MD1209 PM EST TUE FEB 11 2014VALID FEB 11/1200 UTC THRU FEB 15/0000 UTC...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIRINGEST...==================================================12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES==================================================NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TOSIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.==================================================...EASTERN U.S. CYCLONE AND WINTER STORM...PREFERENCE: 00Z ECMWF WITH SFC LOW TRACK ADJUSTED 40 MILESSOUTH/EASTDESPITE BOTH NORTHERN AND SOUTHERN STREAM SHORTWAVES HAVINGENTERED THE NORTH AMERICAN UPPER AIR NETWORK...SOME SIGNIFICANTMODEL DIFFERENCES REMAIN. WHAT WE DO KNOW WITH CONFIDENCE IS THATTHIS STORM WILL PRODUCE VERY DISRUPTIVE ACCUMULATIONS OF ICE ANDSNOW OVER A BROAD SWATH AFFECTING THE SOUTHERN U.S. AND THE EASTCOAST STATES. CONCEPTUALLY THE MODELS INDICATE SIMILAR IDEAS TOONE ANOTHER...WITH SURFACE LOW DEVELOPMENT STARTING ALONG THECENTRAL GULF COAST AROUND 12/12Z AND THE CYCLONE THEN DEEPENING ASIT TRACKS ACROSS THE FAR SOUTHEAST STATES TOWARD THE OUTER BANKSIN NORTH CAROLINA AND THEN UP THE EAST COAST.THE GFS HAD BEEN ONE OF THE WEAKER SOLUTIONS ESPECIALLY WHENMEASURED BY THE SURFACE LOW DEPTH AND THE LATE ONSET OF A CLOSEDCIRCULATION AT 500 MB. THE GFS HAS TRENDED STRONGER AT THESURFACE...BUT IS STILL SLOW TO CLOSE OFF A LOW AT 500 MB...AND ISCORRESPONDINGLY FASTER IN ITS FORWARD SPEED. THE ECMWF HAS STRONGSUPPORT FROM THE 00Z ECMWF ENSEMBLE MEAN AND THE 00Z UKMET RUNOCCASIONALLY PHASED WITH THE ECMWF...ESPECIALLY ALONG THE MIDATLANTIC COAST. STILL...IT IS DIFFICULT TO MOVE OUR PREFERENCEENTIRELY TOWARD THE ECMWF...DESPITE ITS RELATIVE CONSISTENCY...ASTHERE IS NO PHYSICAL REASON TO EXPECT THAT THE SURFACE CYCLONEWILL DEFINITELY SPIN UP AS EARLY AND AS SYMMETRICALLY AS IT DOESIN THE ECMWF SOLUTION. MANY OTHER SOLUTIONS SUCH AS THENAM/SREF/GFS/UKMET HAVE INDICATED A MORE ELONGATED LOW EARLY INTHE PROCESS...STRETCHED OUT ALONG THE PRE-EXISTING FRONTAL ZONE INTHE SOUTHERN STATES.ONE WAY TO RESOLVE THESE DIFFERENCES IS TO TAKE THE CHARACTER ANDINTENSITY OF THE ECMWF SOLUTION AND SHIFT IT JUST SLIGHTLY SOUTHAND EAST TOWARD MORE OF A CONSENSUS TRACK.THE NAM HAS FALLEN NEAR CONSENSUS ON OCCASION...BUT THE 12Z RUNDID NOT. IT IS THE FLATTEST MODEL WITH THE SOUTHERN STREAMSHORTWAVE THAT SPURS THIS DEVELOPMENT OVER THE SOUTHEAST...WHICHYIELDS A FAST AND WEAK SYSTEM OVERALL. IT IS NOT RECOMMENDED TOPUT MUCH IF ANY WEIGHT ON THE NAM AFTER DAY 1.
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Pending complete 12z review.  HPC/WPC Model Discussion.

MODEL DIAGNOSTIC DISCUSSIONNWS WEATHER PREDICTION CENTER COLLEGE PARK MD1209 PM EST TUE FEB 11 2014VALID FEB 11/1200 UTC THRU FEB 15/0000 UTC...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIRINGEST...==================================================12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES==================================================NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TOSIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.==================================================...EASTERN U.S. CYCLONE AND WINTER STORM...PREFERENCE: 00Z ECMWF WITH SFC LOW TRACK ADJUSTED 40 MILESSOUTH/EASTDESPITE BOTH NORTHERN AND SOUTHERN STREAM SHORTWAVES HAVINGENTERED THE NORTH AMERICAN UPPER AIR NETWORK...SOME SIGNIFICANTMODEL DIFFERENCES REMAIN. WHAT WE DO KNOW WITH CONFIDENCE IS THATTHIS STORM WILL PRODUCE VERY DISRUPTIVE ACCUMULATIONS OF ICE ANDSNOW OVER A BROAD SWATH AFFECTING THE SOUTHERN U.S. AND THE EASTCOAST STATES. CONCEPTUALLY THE MODELS INDICATE SIMILAR IDEAS TOONE ANOTHER...WITH SURFACE LOW DEVELOPMENT STARTING ALONG THECENTRAL GULF COAST AROUND 12/12Z AND THE CYCLONE THEN DEEPENING ASIT TRACKS ACROSS THE FAR SOUTHEAST STATES TOWARD THE OUTER BANKSIN NORTH CAROLINA AND THEN UP THE EAST COAST.THE GFS HAD BEEN ONE OF THE WEAKER SOLUTIONS ESPECIALLY WHENMEASURED BY THE SURFACE LOW DEPTH AND THE LATE ONSET OF A CLOSEDCIRCULATION AT 500 MB. THE GFS HAS TRENDED STRONGER AT THESURFACE...BUT IS STILL SLOW TO CLOSE OFF A LOW AT 500 MB...AND ISCORRESPONDINGLY FASTER IN ITS FORWARD SPEED. THE ECMWF HAS STRONGSUPPORT FROM THE 00Z ECMWF ENSEMBLE MEAN AND THE 00Z UKMET RUNOCCASIONALLY PHASED WITH THE ECMWF...ESPECIALLY ALONG THE MIDATLANTIC COAST. STILL...IT IS DIFFICULT TO MOVE OUR PREFERENCEENTIRELY TOWARD THE ECMWF...DESPITE ITS RELATIVE CONSISTENCY...ASTHERE IS NO PHYSICAL REASON TO EXPECT THAT THE SURFACE CYCLONEWILL DEFINITELY SPIN UP AS EARLY AND AS SYMMETRICALLY AS IT DOESIN THE ECMWF SOLUTION. MANY OTHER SOLUTIONS SUCH AS THENAM/SREF/GFS/UKMET HAVE INDICATED A MORE ELONGATED LOW EARLY INTHE PROCESS...STRETCHED OUT ALONG THE PRE-EXISTING FRONTAL ZONE INTHE SOUTHERN STATES.ONE WAY TO RESOLVE THESE DIFFERENCES IS TO TAKE THE CHARACTER ANDINTENSITY OF THE ECMWF SOLUTION AND SHIFT IT JUST SLIGHTLY SOUTHAND EAST TOWARD MORE OF A CONSENSUS TRACK.THE NAM HAS FALLEN NEAR CONSENSUS ON OCCASION...BUT THE 12Z RUNDID NOT. IT IS THE FLATTEST MODEL WITH THE SOUTHERN STREAMSHORTWAVE THAT SPURS THIS DEVELOPMENT OVER THE SOUTHEAST...WHICHYIELDS A FAST AND WEAK SYSTEM OVERALL. IT IS NOT RECOMMENDED TOPUT MUCH IF ANY WEIGHT ON THE NAM AFTER DAY 1.

 

it's always hard to take an old run over a new run...and I realize they haven't fully updated for the 12z.  It was a good thought but with the Euro going warm and losing the "character" it had...ugh.

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Pending complete 12z review.  HPC/WPC Model Discussion.


 

 

Ha ha, light dawns on marble head, re the ending statement there...   j/k.  "IT IS NOT RECOMMENDED TO

PUT MUCH IF ANY WEIGHT ON THE NAM AFTER DAY 1."   Classic!

 

Yeah, I offer the reasoning for some that "elongation" is convective feedback.  The origin of this system so deep in the south is going to excite some explosive convection and it is going to be hard for some models (depending on their convective parameterization types) to iron out truth from fiction (so to speak...).  

 

The NAM is a very efficient convective initialization tool in the summer, and some of that superior skill lops over to (ironically) detract from it's synoptic scale system processing skill; particularly when those larger-scaled systems are in their zygote phases... It gets fed the variables, and then it goes nuts in its native parameterization ... ultimately causing it to wonder off like boat with no one at the helm..  Sometimes convection does feed back and alter systems, sometimes it does not.  Most models at one point or another roll dice to figure out if "now" is one of those times, or not.  The NAM has weighted di though

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You can see how a decrease in omega effects temp profiles. Big lift fights off warmth, so you lose dynamics and you allow warmer air to penetrate inland. This is partly what the GFS was doing, especially the earlier runs. The front end job didn't change that much, it's just that the mix and dryaslot get further west.

 

I still have a hard time with a bowling ball near Hatteras, but it's not impossible. It will be interesting to see if ensembles agree.

giv3n that we are now under 48 hours, this is probably the last ensembles run that will really matter.  ?

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